1. Field of the Invention
The invention relates to a powder inhaler having at least one specially sharpened needle for the precise piercing or cutting open of capsules and hence for the optimum delivery of powdered medicament compositions, medicament formulations or medicament mixtures.
2. Description of the Prior Art
Powder inhalers are known from the prior art. For example, EP 0 703 800 B1 and EP 0 911 047 A1 disclose a powder inhaler consisting of a dish-shaped lower part and an equally dish-shaped cover. After placing the capsule in the capsule holder the patient can press an actuator which is movable from a resting position and thereby cooperates with at least one needle that can be pressed into the capsule holder. The capsule is pierced by the needle or needles and the drug is released.
Other inhalers are known by the brand names Spinhaler®, Rotahaler®, Aerolizer®, Flowcaps®, Turbospin®, AIR DPI®, Orbital®, Directhaler® and/or described in DE 33 45 722, EP 0 591 136, DE 43 18 455, WO 91/02558, FR-A-2 146 202, U.S. Pat. No. 4,069,819, EP 666085, EP 869079, U.S. Pat. No. 3,991,761, WO99/45987, WO 200051672, Bell, J. Pharm. Sci. 60, 1559 (1971); Cox, Brit. Med. J. 2, 634 (1969).
In medicine, needles are known for all kinds of applications, whether for diagnosis (biopsies), treatment (injection) or for perforating or cutting open capsules which are used in inhalers.
When perforating or cutting open a capsule, in contrast to perforating human or animal skin, it is always particularly important to produce a large, precise puncture hole for releasing the powder from the capsule as completely as possible.
A precise puncture hole or cut cannot be obtained using a blunt needle as experience has shown that this will only indent and damage the capsule. It would not then be possible to deliver the powder and hence the medicament, medicament formulation or medicament mixture.
The needle must also be specially sharpened for perforating or cutting open a capsule precisely, so as to ensure that the powder is subsequently expelled as completely as possible.
German Standard DIN 13097 contains ground rules for types of sharpening for medical cannulas for injection and transfusion from rigid and semi-rigid materials. These types of sharpening are simple, faceted and relief-ground sharpening. In addition there is the European standard EN ISO 7864 for sterile single-use injection cannulas.
Special needles for puncturing medicament capsules for use in powder inhalers are known for example from German Utility Model DE 20 2004 005 618. These are solid material needles with a bevelled basic point and two front faceted points with specially defined sharpening angles.
The task of the capsules is to protect the entire inhalable formulation that contains the active substance from chemical or physical changes before a patient inhales the formulation.
The capsule generally consists of two parts, a capsule body (body) and a capsule cap (cap), which are fitted together telescopically. However, multi-part capsules are also known.
The capsule material is a gelatin, particularly hard gelatin. For certain special applications, easily digested water-soluble plastics are used as the capsule material for use in humans, so as to release the active substance in certain parts of the gastro-intestinal tract when it is administered by oral route.
The following are examples of different capsule materials:
EP 0460921 describes capsules of chitosan and starch, cereal powder, oligosaccharides, methacrylic acid methyl acrylate, methacrylic acid ethyl acrylate, hydroxypropylmethylcellulose acetate, succinate or phthalate. The capsule material is characterised in that the contents are only released in the large intestine.
GB 938828 discloses capsules for radioactive substances used therapeutically or diagnostically. The capsules consist of water-soluble gelatine, methylcellulose, polyvinylalcohol or water-soluble non-toxic thermoplastics.
WO 00/07572 discloses capsules for inhalers, which consist of non-digestible plastics.